Vegetation changes in an abandoned montane grassland, compared to changes in a habitat with low-intensity sheep grazing – a case study in Styria, Austria
In protected areas maintaining existing phytodiversity is an important conservation target. In this study we analysed the effects of abandonment on plant species composition and species richness over a period of nine years in a montane grassland in the Long-term Ecosystem Research (LTER) region Eisenwurzen (Styria, Austria). Additional investigations concerned the number of Red Data List species, plant strategy types, Ellenberg indicator values, indicator values for mowing, grazing and trampling tolerance, temporal sequence of phenological phases and seven plant traits. We differentiated two topography-related habitat types: an initially species-rich sheep pasture on a steep, south-facing slope and a less species-rich meadow on a flat site immediately below, with a comparatively higher nutrient and water supply in the topsoil. Testing a possible management alternative, the effects of continued low-intensity sheep grazing on the slope were also analysed. In spring 2001, one permanent plot of 50 m² was established in the centre of each habitat type and treatment. Our results show that the long-term effects of abandonment on grassland vegetation depend largely on local site conditions. Nutrient availability in the soil seems to be an especially important factor. On the abandoned flat site, floristic composition and physiognomy changed dramatically within four years; a high species turnover and a decline in phytodiversity could be observed. In contrast, we found only minor effects on the abandoned slope site even nine years after abandonment. If the maintenance of existing phytodiversity is a conservation target, suitable management operations have to be carried out at shorter intervals (at least every 3 years) in habitats with nutrient-rich soils than in nutrient-poor habitats (approx. 5 to 10 years). From a nature conservation point of view, low-intensity sheep grazing may be a suitable management alternative to mowing.
Schlagworte: abandonment, permanent plots, secondary succession, species turnover, management operations